This artist's map of the Milky Way shows the location of one of the farthest known exoplanets
This artist's map of the Milky Way shows the location of one of the farthest known exoplanets, lying 13,000 light-years away. Most of the thousands of exoplanets discovered to date are closer to our solar system, as indicated by the pink/orange areas.

Image Credit: NASA/JPL-Caltech

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Astronomers have found an exoplanet nearly 13,000 light-years away, making it one of the most distant planets known to man. This discovery is important not because of the planet itself, a gas giant about half the size of Jupiter, but because what it means for the future of planetary discovery and mapping.

Astronomers working on the project exploited a phenomenon known as microlensing, which occurs when one star passes in front of another and the closer star’s gravity acts as a magnifying glass and bends the light of the more distant star, causing it to appear brighter. If that nearer star is orbited by a planet it will cause a disturbance in the magnified light.

"Microlensing experiments are already detecting planets from the solar neighborhood to almost the center of the Milky Way," co-author Andrew Gould of The Ohio State University, Columbus, said in a statement. "And so they can, in principle, tell us the relative efficiency of planet formation across this huge expanse of our galaxy."

However, microlensing is not an effective way to pinpoint the location of planets. Nearly half of the planets detected using that method do not have a corresponding location.

That is why having two telescopes witness the event is vital. By using the OGLE in Chile and the Spitzer Space Telescope in orbit around the Earth, astronomers were able to use the time between each telescope’s observation of the event to determine the location of the planet with extreme accuracy.

With the ability to calculate the location of exoplanets so accurately, this pair of telescopes has the potential to determine how planets are distributed throughout the Milky Way, a flat, spiral-armed galaxy.

"We don't know if planets are more common in our galaxy's central bulge or the disk of the galaxy, which is why these observations are so important," NASA Sagan Fellow Jennifer Yee said in a statement.

The Spitzer telescope is scheduled to watch approximately 120 more microlensing events this summer, which could lead to further exoplanet discoveries.

"We've mainly explored our own solar neighborhood so far," Sebastiano Calchi Novati, a Visiting Sagan Fellow at NASA's Exoplanet Science Institute at the California Institute of Technology, said in a statement. "Now we can use these single lenses to do statistics on planets as a whole and learn about their distribution in the galaxy."